A R Harvey Blog

Westminster Time-Lapse

I've been meaning to do some time-lapse work for a while now, and last weekend I headed down to Embankment bridge. Looking south one can spot Big Ben, the Houses of Parliament and the London Eye.

I was particularly keen to catch the dazzling motion blur of car headlights. This meant long exposures, so I set the shutter speed to half the frame interval. Conventional film and video cameras usually operate with the shutter open for half the frame.

My intervalometer was a PocketWizard MultiMax. Normally these are used for wirelessly triggering flashes, but the bells'n'whistles MultiMax can also be connected to a camera's shutter release.

The video above demonstrates four time-lapse speeds (shutter/interval): 0.4sec/0.8sec, 2sec/4sec, 4sec/6sec and 4sec/8sec. Each clip is ten seconds (250 frames at 25fps) long.

I've also added a subtle amount of "camera drift" in post. It's as though I am on the bridge holding the camera. A little movement definitely helps bring the scene to life.

Camera Limitations

I experimented with a variety of intervals, from 0.4sec to 8sec. At the fast end I encountered problems. One was that my camera - a Canon 5D MkI - had trouble writing the JPEGs to card fast enough; the memory buffer would fill up, preventing the camera from taking more shots until space became available. I worked around this by setting the JPEG size to Small, thereby reducing the amount of data that had to be saved. A small JPEG on the 5DMkI is still large enough to comfortably accomodate a 1080p HD video frame. The second problem involved the lag of the camera's mechanism. Although the shutter speed may be set to 0.2sec, additional time is required to flip the mirror up and return it to rest afterwards. With such a relatively long shutter speed, a frame interval of 0.4sec was insufficient. The camera missed every other shot.

Post-Production Workflow

Another motivation for this test was to put my DSLR Stills -> Video -> Web workflow through it paces. The goal was to arrive at a colour-accurate 720p HD version online, in this case using Vimeo. The full details are beyond the scope of this short blog post but needless to say, colour management was a major headache. In the film and video world, the delivery target is usually better defined. More assumptions can be made. Colour management is therefore approached rather differently, and some may say, more loosely. Final Cut Pro for example has no concept of colour management, instead relying on the operator to use monitors calibrated to a specific target. Apple Compressor also expects to receive video in a certain colour space.

Nevertheless, I spent a couple of days investigating the problem and managed to cobble together a solution. Further work is required to streamline the workflow though and test it with some proper colour cards.

Charing Cross Road, Painting with Light

Charing Cross Road (long exposure). Canon TS-E 24mm f/3.5L tilt-shift lens.

Car head lights render the buildings with a painterly light. Pedestrians evaporate from the sidewalk.

In the dark our eyes lose their sensitivity to colour. Bright lights dazzle us. Yet the camera can see beyond this, revealing colour and detail that moments before was hidden to our senses.

The Folly of Self Portraits

I have been debating with myself whether to post the above portrait. Although I look very earnest, the photo is meant to be anything but.

Recently I invested in a honeycomb grid reflector set. The grids, which slot onto the front of the reflector, narrow the beam of light. There are three to choose from, and each produces a different angle of spread. I was eager to try them out, and in lieu of a model, I had to use myself.

Cindy Sherman I am not.

In the Realm of Shadow and Silhouette

In addition to freezing motion, Vicki and I also explored the realm of shadow.

The holy trinity of key, fill and back light is well established. It is the classic, textbook lighting setup. However it does get tired pretty quickly. The back light defines the form of the subject's shadow side - it adds dimension and separates the foreground from the background. This is the conventional wisdom.

But is it the only way of defining form? Of course not.

For our shoot, I eliminated fill and back lighting entirely. Instead of fighting the resulting silhouette I chose to embrace it, using the crisp, dark outline to define the shape of Vicki's body. What can be done with light can often be done with shadow too, it seems. A few more examples can be seen in my post on freezing motion.

Using shadow to remodel the face.

Creative Constraints and Motion Freeze

It is important to be flexible and hunt for opportunities where others see constraints.

When Vicki and I got together last week to do a series of fashion and portrait shots we had no stylist, no make-up artist, and no hair stylist. There is rather negative attitude held by some that in order to take engaging photos you need a full entourage of specialists. I have to disagree. All it means is that you have to be realistic, and understand what is possible with the resources at hand.

Clearly high-end beauty shots were out of reach - you need a skilled make-up artist for those. There was no point us trying anything that required precision hair styling either. So we threw ourselves the other way entirely, doing things that would deliberately mess the hair and work the entire body. We used the constraints as a creative tool.

Motion freeze employs a combination of fast shutter speeds and strobes to capture a rarified moment in time. Almost everyone has seen pictures of balloons been punctured by bullets and water drops splashing upon hard surfaces. I wanted to try something in the same spirit with Vicki.

Freezing movement is not quite as straight forward as simply cracking out the strobes. Indeed, there is a common belief that flash is near instantaneous, and that when a pulse fires, it reaches maximum intensity immediately. Sadly this is not the case. Each pulse lasts a finite amount of time. Its duration varies with intensity. Brighter pulses last longer than weaker ones, and the bulb requires a certain amount of time to reach full intensity.

For regular portraiture and fashion shots, this is not a problem - the model poses quietly and all is well. As soon as she starts leaping in the air and spinning around though, the realities of the finite strobe pulse begin to manifest themselves.

Short of investing in very expensive, top of the range strobes - which can easily cost north of £10k - there are other options. The easiest way to shorten the pulse is to simply lower the power. Yet the ramifications are many. Does one compensate by opening up the iris, narrowing the depth of field? Or does one use a higher ISO setting, thereby increasing noise? Should a wider angle be employed to claw back some depth of field? The lower the strobe intensity, the more prevalent the ambient light; can this too be kept under control?

Fundamentally, the less light one has to work with, the greater the compromises.

More photos from the shoot are included in my post on shadow and silhouette.

Thanks to Adam Orzechowski for technical advice.

Soft Light Portraits

Last weekend my housemates and I hosted another party. I thought it would be a fun idea to set up a small portrait studio in my bedroom and invite people to have their pictures taken.

My hope was that the alcohol would lower people's inhibitions. I wanted to catch fleeting moments, rare insights - something to remember a person by. 

Very few of us have immaculate skin. Nor are we likely to possess the hand of a professional makeup artist. The challenge was to rig a lighting setup that would flatter normal, everyday skin. I certainly had no appetite for retouching blemishes and dry patches. My solution involved two studio lights and a giant light box constructed out of 8ft x 4ft polyboards. The idea was to bathe each subject in a wash of soft light.

One strobe was positioned just left of camera and fitted with a beauty dish. Although I was creating a wash of light, I still wanted to preserve a hint of definition. The clean, even light of the beauty dish is great for pricking moist eyes and teasing out the structure of the face. On shiny skin it produces gorgeous, rounded reflections (see photo above.) The second strobe rested on the floor by the foot of the rear polyboard, tilted upward. It's purpose was to simply blast the background area with light.

It all felt rather odd. Usually I find myself fighting spill light; yet here I was doing everything possible to encourage it.

The soft-light studio.

LED Light Trail Tests

I have always wanted to experiment with Light Emitting Diodes (LEDs) and long exposures. Unlike incandescent bulbs - the sort that light your hallway - LEDs use very little power and give off next to no heat. They are hardy too. The actual light source is encapsulated within a solid plastic casing. With the appropriate measures in place, you can whack them, stamp on them, and drown them. And since they are so tiny, you can mount dozens of them onto regular cardboard to create interesting effects.

The only slightly tricky bit is wiring them up.

Here is something I cobbled together a few days back. It is a single, blue LED on the end of a 4m long cable. The cable is black so that it won't show up in the photo. It is also long enough to be swung around and generally mishandled. On the other end is a simple electronics circuit.

Batteries are best for this sort of thing because they are cheap, light, portable and cannot electrocute you. The alternative would be a cumbersome power supply unit connected to the mains. The small microchip next to it is a 555 timer. By the mere flick of a switch, the LED will begin to flash on and off. The two knobs on the right control the timing.

Anyway, enough of the science. Here are some of the results. Obviously I am not trying to capture award-winning photos just yet - this is just a test.

By the way, check out this Light Graffiti.

(All photos taken with a Canon 5D + 24-70mm f/2.8 L USM lens.)